© Department of Physiology
Faculty of Medicine
Masaryk University
2016
M. Bébarová
XXII. Measurement of basal
metabolic expenditure (BME)
using indirect calorimetry
XXIII. Calculation of energy
expenditure
 direct and indirect calorimetry
 metabolic expenditure: basal vs. resting
 catabolism/anabolism
 energy balance
 nitrogen balance
 energetic equivalent of oxygen
 basal conditions
Direct calorimetry
 Works on presumption that all
metabolic actions are accompanied by
heat production
 Technically demanding
 In practice, often not used
Indirect calorimetry
 Works on presumption that
consumption of oxygen, CO2
production and nitrate metabolites
waste correspond to the energetic
output
- Open or closed cycle setup
- In practicals: closed system setup
using Krogh respirometer
Caloric (energetic) equivalent of oxygen
(EE)
 For mixed diet
 = amount of energy released during
consumption of 1 L of oxygen:
 EE = 20.19 kJ/L O2
Basal metabolism
 Energetic expenditure of organism
established in defined (basal)
conditions:
 Thermoneutral environment
 12-18 hours after the last meal containing
proteins
 Psychological and social well-being,
optimally in the morning before leaving the
bed
Actual energy expenditure (AEE)
1) at rest
2) at standing
3) after workload
 estimate the oxygen consumption (l/s)
 correct the measured values to 0 C and
101,325 kPa
(for the formula see Physiology and Neuroscience
Practicals, 2013 – page 87)
 calculate AEE (kJ/s, kJ/day)
 explain differences in AEE observed in
different conditions
Calculation of energy expenditure
1) basal energy expenditure (BEE)
2) actual energy expenditure (AEE)
 according to Harris-Benedict formula
(Physiology and Neuroscience Practicals, 2013 – page 89)
 kcal/day - transform to kJ/day (1 kcal = 4.18 kJ)
 may be calculated based on:
- BEE
- AF (activity factor)
- TF (temperature factor)
- IF (injury factor)